Regular undergarments in current use are made of cotton and/or synthetic materials. The cotton and synthetic panties typically do not offer barrier protection. Often the synthetic panties have a cotton lined crotch to absorb vaginal discharges or perspiration. The absorbent/barrier properties of regular undergarments are minimal such that any vaginal discharge and/or heavy perspiration may strike through onto outer clothing (i.e., penetration of liquid from the interior to the exterior of the panty.)
Panty liners and feminine care sanitary napkins or pads used with regular undergarments have polyethylene backings that provide some barrier properties needed to prevent liquid strike through. However, if the vaginal discharge extends to the sides or the ends of the pads it can leak onto the undergarment. This leakage can stain the undergarment. Depending upon the amount of leakage, liquid may strike through or go around the undergarment to stain outer clothing and/or bedding. Women with heavy periods often use one or more maxi pads, double pads and/or tampons alone, or in combination, and change these pads and tampons frequently to prevent embarrassing, messy leakage and/or staining of outer clothing. In some cases, during their heaviest flow days, women will restrict their activities and stay home.
A majority of women experience some leakage of menses from their pads to their undergarments. This varies from being limited to a small number of pads leaking onto only the undergarment during light flow to leakage onto the wearer's outer clothing on almost half the pads worn during heavy flow. Normally this leakage occurs at the side of the product, although end leakage is also a problem. Placement of maxi pads and overnight pads in the crotch of regular undergarments shows that, at best, the pads lay on the leg elastic and, at worst, overhang the leg elastics. This causes side leakage onto the undergarment and possibly onto outer clothing. Typical leakage from the pads is caused by poor fit of the pad to the body, improper positioning of the pad by the user and lack of absorbency. Leakage from the undergarment onto the outer clothing is due to incompatibility between the pad width and the panty crotch width and lack of barrier properties in the panty material around the edge portion of the pad.